How do I scan my Linux system for rootkits, worms, trojans, etc.?

Publicado: novembro 9, 2007 em howto

Either with chkrootkit or with rkhunter.

chkrootkit

Either install the package that comes with your distribution (on Debian you would run)

apt-get install chkrootkit

, or download the sources from www.chkrootkit.org and install manually:

wget –passive-ftp ftp://ftp.pangeia.com.br/pub/seg/pac/chkrootkit.tar.gz
tar xvfz chkrootkit.tar.gz
cd chkrootkit-<version>/
make sense

Afterwards, you can move the chkrootkit directory somewhere else, e.g. /usr/local/chkrootkit:

cd ..
mv chkrootkit-<version>/ /usr/local/chkrootkit

Now you can run chkrootkit manually:

cd /usr/local/chkrootkit
./chkrootkit

(if you installed a chkrootkit package coming with your distribution, your chkrootkit might be somewhere else).

You can even run chkrootkit by a cron job and get the results emailed to you:

Run

crontab -e

to create a cron job like this:

0 3 * * * (cd /usr/local/chkrootkit-<version>; ./chkrootkit 2>&1 | mail -s "chkrootkit output my server" you@yourdomain.com)

That would run chkrootkit every night a 3.00h.

Results

webserver:/etc# /usr/sbin/chkrootkit
ROOTDIR is `/’
Checking `amd’… not found
Checking `basename’… not infected
Checking `biff’… not found
Checking `chfn’… not infected
Checking `chsh’… not infected
Checking `cron’… not infected
Checking `crontab’… not infected
Checking `date’… not infected
Checking `du’… not infected
Checking `dirname’… not infected
Checking `echo’… not infected
Checking `egrep’… not infected
Checking `env’… not infected
Checking `find’… not infected
Checking `fingerd’… not found
Checking `gpm’… not found
Checking `grep’… not infected
Checking `hdparm’… not infected
Checking `su’… not infected
Checking `ifconfig’… not infected
Checking `inetd’… not infected
Checking `inetdconf’… not infected
Checking `identd’… not found
Checking `init’… not infected
Checking `killall’… not infected
Checking `ldsopreload’… not infected
Checking `login’… not infected
Checking `ls’… not infected
Checking `lsof’… not infected
Checking `mail’… not infected
Checking `mingetty’… not found
Checking `netstat’… not infected
Checking `named’… not found
Checking `passwd’… not infected
Checking `pidof’… not infected
Checking `pop2’… not found
Checking `pop3’… not found
Checking `ps’… not infected
Checking `pstree’… not infected
Checking `rpcinfo’… not infected
Checking `rlogind’… not found
Checking `rshd’… not found
Checking `slogin’… not infected
Checking `sendmail’… not infected
Checking `sshd’… not infected
Checking `syslogd’… not infected
Checking `tar’… not infected
Checking `tcpd’… not infected
Checking `tcpdump’… not infected
Checking `top’… not infected
Checking `telnetd’… not found
Checking `timed’… not found
Checking `traceroute’… not infected
Checking `vdir’… not infected
Checking `w’… not infected
Checking `write’… not infected
Checking `aliens’… no suspect files
Searching for sniffer’s logs, it may take a while… nothing found
Searching for HiDrootkit’s default dir… nothing found
Searching for t0rn’s default files and dirs… nothing found
Searching for t0rn’s v8 defaults… nothing found
Searching for Lion Worm default files and dirs… nothing found
Searching for RSHA’s default files and dir… nothing found
Searching for RH-Sharpe’s default files… nothing found
Searching for Ambient’s rootkit (ark) default files and dirs… nothing found
Searching for suspicious files and dirs, it may take a while…
/lib/init/rw/.ramfs

Searching for LPD Worm files and dirs… nothing found
Searching for Ramen Worm files and dirs… nothing found
Searching for Maniac files and dirs… nothing found
Searching for RK17 files and dirs… nothing found
Searching for Ducoci rootkit… nothing found
Searching for Adore Worm… nothing found
Searching for ShitC Worm… nothing found
Searching for Omega Worm… nothing found
Searching for Sadmind/IIS Worm… nothing found
Searching for MonKit… nothing found
Searching for Showtee… nothing found
Searching for OpticKit… nothing found
Searching for T.R.K… nothing found
Searching for Mithra… nothing found
Searching for OBSD rk v1… nothing found
Searching for LOC rootkit… nothing found
Searching for Romanian rootkit… nothing found
Searching for Suckit rootkit… nothing found
Searching for Volc rootkit… nothing found
Searching for Gold2 rootkit… nothing found
Searching for TC2 Worm default files and dirs… nothing found
Searching for Anonoying rootkit default files and dirs… nothing found
Searching for ZK rootkit default files and dirs… nothing found
Searching for ShKit rootkit default files and dirs… nothing found
Searching for AjaKit rootkit default files and dirs… nothing found
Searching for zaRwT rootkit default files and dirs… nothing found
Searching for Madalin rootkit default files… nothing found
Searching for Fu rootkit default files… nothing found
Searching for ESRK rootkit default files… nothing found
Searching for rootedoor… nothing found
Searching for ENYELKM rootkit default files… nothing found
Searching for anomalies in shell history files… nothing found
Checking `asp’… not infected
Checking `bindshell’… not infected
Checking `lkm’… chkproc: nothing detected
Checking `rexedcs’… not found
Checking `sniffer’… lo: not promisc and no packet sniffer sockets
eth0: not promisc and no packet sniffer sockets
Checking `w55808’… not infected
Checking `wted’… chkwtmp: nothing deleted
Checking `scalper’… not infected
Checking `slapper’… not infected
Checking `z2’… chklastlog: nothing deleted

rkhunter

Download the latest rkhunter sources from www.rootkit.nl:

wget http://downloads.rootkit.nl/rkhunter-1.2.7.tar.gz
tar xvfz rkhunter-1.2.7.tar.gz
cd rkhunter/
./installer.sh

This will install rkhunter to the directory /usr/local/rkhunter. Now run

rkhunter –update

to download the latest chkrootkit/trojan/worm signatures (you should do this regularly).

Now you can scan your system for malware by running

rkhunter -c

 

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